In 1955, two Australian scholars, Rose and Nelson, developed an osmotic pump for administration to livestocks. In 1970's, the osmotic pump was simplified by Alza Co. In 1974, Theeuwes developed a single-chamber osmotic pump, which was in a simple form of ordinary coated tablet with one side being drilled. Thus, osmotic pump became a dosage form that could be used in clinic, and therefore a series of single-chamber controlled osmotic pump tablets dosage forms were developed. From 1980's, the modification and development about osmotic pump never stopped. In order to prepare insoluble drug into osmotic pump, or to prepare drug with good water solubility but cannot produce osmotic pressure by itself into osmotic pump, a single-chamber bilayer osmotic pump was developed. In order to release drug stably, a double-chamber osmotic pump was developed. In order to be adapted to circadian rhythm of human body, a timed-release osmotic pump was developed, and so on.
A series of defects exist in the preparation of controlled osmotic pump tablets by laser drilling process, for example, (1) a high cost: a device for laser drilling costs above one million Yuan; moreover, an usual carbon dioxide laser device can only generate excitation for 5×105 times in its service life, if one tablet is drilled once, one laser tube can only be used to produce 2 to 3 batches of drugs; the cost and maintenance charge of the device are quite expensive; (2) a low yield and a great labor intensity: laser drilling inevitably has the problems of missed drilling (in the case of the tablets being not tightly caught by a collector and falling off), over drilling (in the case of the tablets being not cleared away from the drilling place by a sweeper in time), depth of drilling being insufficient (in the case of reduced laser energy) to penetrate the semipermeable membrane, wrong drilling position, and etc., thus a relatively low yield is resulted. Since there isn't a process now to automatically screen out unqualified osmotic pumps, the tablets having the problems of missed drilling, over drilling, wrong drilling position and insufficient depth of drilling must be screened out manually during the production. This is a job that quite consumes time and involves a great effort. In general, one batch of samples includes 2×105 tablets, and the job of manually screening out unqualified tablets needs 7 days to be accomplished, which involves quite high labor intensity.
Although the design of osmotic pump is very ingenious, various shortcomings, for example, too many procedures involved in the industrialized production thereof, strict requirements on the indexes of controlling each procedure, great difficulty involved in the production, long production period, high cost, and high rate of rejects, seriously restrict the extension of osmotic pump product. As can be seen from the development course of osmotic pump, the industrialization of osmotic pump is accelerated by each time of simplification on the structure and process of osmotic pump, thus the development of osmotic pump having simple structure, low difficulty in industrialized production, and low production cost is an important tendency in the field.